This invention pertains to fence systems and more particularly to fence systems including panels attachable to frames with the panels also being attachable over existing woven fabric fence material.
Fence systems and fence materials come in a wide variety of configurations. One of the most common types of fence systems uses chain link fence material (also known as hurricane or cyclone fencing). The chain link fence system includes a woven "chain link" fence material which is stretched over and attached to a structural frame. The woven material includes a series of interlinking fence pickets. The fence pickets have a characteristic zig-zag pattern which facilitates the interlinking of the pickets. Each of the interlinking pickets is an independent body which is woven with neighboring pickets on each side. Often, terminal portions of the pickets are twisted on one end and knuckled on the other end to help retain the woven structure.
A frame used with a chain link fence system includes a series of vertical and non-vertical segments or posts and rails. The woven material is unrolled from large bails of material and cut to a desired length. Cutting involves separating the twisted terminal ends of the pickets or cutting off such terminal ends and unweaving one of the pickets from its neighbors. The selected piece of woven material is placed against the frame and stretched to mount the material against the frame in a tensioned manner. In this regard, the chain link fabric must be tensioned between at least two vertical segments of the frame.
The chain link fence system has several problems. First, the woven material, while providing a degree of deterrence, can be defeated quite easily. Because the chain link system employs a woven material, removal of one of the pickets allows a portion of the fence to be unraveled or spread apart in a curtain-like manner. As noted above, the pickets are easily removable by removing terminal ends of each picket and merely unweaving the picket from its neighboring pickets.
An informal study indicates that a person skilled at penetrating chain link fence systems can create an opening in the woven material sufficient to drive a small car through in less than one minute.
An additional problem with the woven material used in chain link fencing systems is that it is easily climbable. The size and orientation of the chain link material forms a space sufficient for gripping and for providing a toehold to ease a climbers ascent. Additionally, the pickets are formed of a rounded wire material which provides a comfortable grip with no deterrent effect. As a result of these characteristics of the chain link material an intruder can quickly and easily climb the chain link fence system.
Various top cap barriers have been created in an attempt to deter climbing over the top of chain link fence systems. One type of top cap barrier employs an unraveled coil of barbed or razor tape wire mounted to the top of the chain link material. In many cases, the razor wire can be spread or pushed out of the way thus allowing a skilled intruder to easily pass over this type of top cap barrier.
In an attempt to overcome the ease which an intruder can pass over the coiled top cap material, an angled top cap was devised employing a series of barbed wire or razor tape wire rows. Once again, a sufficiently skilled and motivated intruder can actually employ these rows to support his weight while climbing over the top of such a structure.
Fence systems are increasingly more important to provide an initial perimeter barrier to secure items of value. As an example, many rail transfer yards are large expansive areas in which large quantities of valuable goods are stored while being transferred within the rail shipping system. Such a temporary storage area is especially prone to theft and vandalism due to the expansive nature of the transfer yard and the inability to constantly monitor all areas of such a facility.
In an attempt to improve security, fences are erected around the perimeter of such a yard to deter casual intrusion. Skilled and motivated intruders easily scale or penetrate ordinary chain link fence systems. Video cameras and electronic monitors are often positioned to provide early warning as to penetration or intrusion. These systems, however, are somewhat easy to foil.
Even when a monitoring system is not foiled by an intruder, often times the size of such a rail transfer yard will result in sufficiently long response time to allow an intruder to steal or vandalize the contents of the yard. A lengthy response time is exacerbated by the extremely short time required to penetrate a chain link fence system. In other words, even though an intruder may be detected as entering the yard, the penetration time is so short and the yard area is so large that a security detail often times cannot get to the scene of the intrusion or theft in sufficient time to apprehend the intruders.
An additional problem with chain link fence systems is that they allow a convenient way for intruders to repeatedly penetrate and exit the perimeter barrier. In this regard, since the woven fence material can be unraveled, it can also be quickly, temporarily reconnected so as to appear to not have been breached. As such, once an intruder opens the woven fabric, if undetected while inside the perimeter, they can exit the same spot and try to repair the spot in an easily disassembled manner to use the same entry point on another visit. The repair can be made using small gauge wire which can be easily cut on the next visit. Often times, containers or other objects placed in front of the repaired point of penetration will obscure the breach in the fencing material from being located during a casual inspection.
As a result of the problems noted above, the defensive abilities of woven fence material of chain link fence systems has declined as the ability and motivation of intruders has increased. Additionally, the cost of securing an area has dramatically increased due to the need to provide additional monitoring of the perimeter barrier including expensive sensing and observation equipment and employees to operate and monitor such equipment. Additionally, even though monitoring equipment is employed, such equipment is prone to vandalism and ordinary break down thereby providing weak links in the overall security system. Due to the intruder skill and motivation of intruders and the frequency of intrusions insurance rates continue to climb. As a result of increasing intrusions, insurance costs and the cost of goods covered by such insurance continue to increase dramatically.
It is highly desirable to provide a fence system which is difficult to penetrate and climb in order to provide a highly reliable perimeter security barrier.